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Detecting cracks of various sizes is crucial for monitoring and predicting rock failure. This study combines two acoustic methods—the passive acoustic emission (AE) and the active ultrasonic P-wave velocity to investigate the cracking process from initiation to propagation and coalescence of rocks containing pre-existing flaws, which simulate the intrinsic defects in natural rocks or rock masses, across different scales in three-dimensional space. The resultant AE activity is found sensitive to microcracks even in the early loading stage and can be divided into three stages: quiet, stable, and high growth periods. The positions of the microcracks can be obtained with the assistance of several AE sensors. It is also found that the P-wave velocity attenuation is more sensitive to macrocracks but less sensitive to microcracks. The results indicate that combining the AE and active ultrasonic-wave methods can provide comprehensive information to evaluate the damage levels and localize the internal cracks with multiple scales in the entire cracking process of rocks. The study also indicates the potential for predicting crack coalescence and failure based on the combination of these two nondestructive methods. In addition, the findings can also be applicable in the monitoring and prediction of failure in other brittle materials. [ABSTRACT FROM AUTHOR]

Granite buried hill oil and gas reservoirs are relatively scarce worldwide, and the fine prediction and characterization of their fractures have always been a significant industry challenge. Particularly in the South China Sea region, large and thick granite buried-hill reservoirs are influenced by various geological processes such as weathering and tectonics, resulting in a complex internal fracture system. The seismic reflection characteristics exhibit high steepness, discontinuity, and significant amplitude differences, posing significant difficulties for the fine characterization of fractures. A systematic and comprehensive research approach has not yet been established. Therefore, this study considers the large granite-buried hill A reservoir in the South China Sea as a typical case study and proposes a multi-scale fracture fine prediction and characterization methodology system. The method starts with analyzing the fracture scale and genesis to refine the fracture scales identifiable by conventional seismic data. Based on this, the U-SegNet model and transfer learning are utilized to achieve fine detection of large-scale fractures. Meanwhile, using highresolution ant tracking technology based on MVMD frequency division and sensitive attribute preferences realizes a fine prediction of medium-to-small-scale fractures. Furthermore, the discrete fracture network is used for fracture deterministic modeling, ranging from geometric morphology to percolation behavior. Ultimately, a post-stack seismic multi-scale fracture prediction and characterization workflow is established. The results indicate that the buried hill in the study area exhibits a high degree of fracture development with evident multi-scale characteristics. Among them, large-scale fractures have a relatively low development density, primarily oriented in the NW and NE directions; medium-to-small-scale fractures exhibit high-density and omnidirectional development. The development of fractures significantly improves the storage space and fluid flow capacity of the buried hill. Compared with traditional methods, the proposed method notably enhances the accuracy of characterizing the degree of fracture development, spatial morphology, and percolation behavior in the buried hill reservoir, providing a scientific basis for oil and gas exploration and development. [ABSTRACT FROM AUTHOR]

The extensive application of vibratory roller compaction in construction has resulted in a requirement to increase the effectiveness of compaction. This paper investigated the effect of the moisture content and the compactive effort on the behaviour of granite particles under compaction. Results from experiments showed that particle crushing depends on the level of imparted energy rather than the number of passes. Increases in the moisture content is not noticeably beneficial to the particle crushing with sufficient compaction but will lead to larger surface settlements with the same imparted energy in the studied range. Test results were used for the construction of the secondary dam in the Huizhou pumped storage power station. [ABSTRACT FROM AUTHOR]

New U–Th–Pb (SIMS)–geochronological, petro-geochemical, and Sr–Nd isotopic data for granitoids of three plutonic complexes (Sakhani, Omchikanda, and Arga–Emneken), located in the joint area of the two large batholih belts of the Verkhoyan–Kolyma fold area, Glavnyi and Severnyi, are presented. The Valanginian–Hauterivian age of the granitoids of all three complexes is established. The similarity of the granites and leucogranites of the Omchikanda and Sakhani complexes to the I–S-type granites and the similarity of the Arga–Emneken granitoids to the I-type granites are shown. The petro-geochemical peculiarities of the granitoid composition indicate a metasedimentary source for the granites and leucogranites of the Omchikanda and Sakhani complexes and a metamagmatic (amphibolitic) source for granitoids of the Arga–Emneken Complex. Sr–Nd isotopic data show that the granitoids were melted from different crustal sources, in which there are various proportions of mature material of the continental crust. The totality of geological and newly obtained geochronological, petro-geochemical, and isotopic data allow us to suppose a collisional setting of their formation in the terminal Valanginian–Hauterivian stage of collision between the Kolyma–Omolon microcontinent and the Siberian continent. [ABSTRACT FROM AUTHOR]

Zirconium (Zr) isotope has significant potential for tracing magmatic processes, particularly late-stage fractionation involving fluids. However, the fractionation of Zr isotopes between magma and fluid is still unclear. In-situ Zr isotope analyses of zircons from three granite-pegmatite suites in the Tibetan plateau show a wide range of δ94/90Zr values (IPGP-Zr) between −0.23 ‰ and +1.38 ‰, with the highest values in hydrothermally altered zircons from pegmatites. A coupled dissolution-reprecipitation process of zircons in a zircon-undersaturated melts is the most plausible mechanism to explain the strong enrichment of heavy Zr isotopes in hydrothermally altered zircons. During the formation of granitic pegmatite, exsolution of F-Na-Si-bearing fluids can enhance zircon solubility and will significantly remove Zr from the melt. Faster diffusion of 90Zr into the fluid channel will result in preferential accumulation of light Zr isotopes in the fluid, and drive the residual melt towards heavier Zr isotopes under disequilibrium conditions. Later, the reprecipitated zircons will inherit the heavy Zr isotope composition of the melt. Rayleigh fractionation models suggest fluid-melt fractionation factors for Zr isotope of about 0.99911–0.99930. This shows the major controls of fluid on Zr isotope fractionation during crystal-magma-fluid differentiation. Thus Zr isotope can be a powerful tracer of the magmatic-hydrothermal transition. [ABSTRACT FROM AUTHOR]

The Cauvery Basin is one of the prolific hydrocarbon-producing basins of southern India. The pericratonic basin has five sub-basins separated by five basement and structural highs formed by granitic and gneissic rocks of the Archaean Southern Granulite Terrane. The sub-basins have excellent Cretaceous source rocks and hydrocarbon-bearing reservoirs of different geological ages. Commercial hydrocarbons are produced from the Archean basement highs, specifically from the Kumbakonam–Madanam palaeo-highs of the Cauvery basin. The paper addresses basement characterisation using conventional as well as advanced well logs for accurate characterisation of the basement reservoirs. Basement reservoirs are challenging in terms of sporadic porosity and permeability distribution. Most of the porosities and permeability are attributed to secondary generation by fracturing and weathering. The present work aims to understand and compare the petrophysical attributes of two kinds of basement reservoirs (fractured basement and weathered basement) on the Kumbakonam–Madanam High. Two wells from each type lying on either side of the Madanam High were selected. Well log data, including gamma-ray, resistivity, porosity (neutron and bulk density), acoustic logs and advanced logs, such as resistivity images and dipole acoustic and elemental capture spectroscopy logs, from these four wells were analysed for their petrophysical understanding. Furthermore, image and acoustic log data were integrated to characterise the fracture geometry and fracture permeability of the basement reservoirs. Conventional log suites showing low GR, low resistivity, high density, and high neutron porosity are indicative of intricate lithologies, possibly mafic rocks. A notable negative crossover in density and neutron log along with excess Si concentration indicates weathering. A higher fracture density with a crisscross fracture/mesh fracture pattern is indicated by the analysis of image logs, shear wave anisotropy, and Stoneley fractures. Thus, a comparison of the petrophysical attributes of both fields is attempted to understand the fractured and weathered basement reservoirs and their geological characteristics. In conclusion, the basement reservoirs of the Madanam High Field are of interest because of their hydrocarbon-producing ability, and proper synthesis of petrophysical attributes will help develop activities in the basement reservoirs. [ABSTRACT FROM AUTHOR]

This research delves into the unexplored geothermal resources within Egypt's internationally significant Red Sea and Central Eastern Desert regions, recognized for their renewable energy prospects. Surface thermal manifestations in granitic rocks, abundant in radioactive minerals, and geothermal anomalies along the depocenter regions of the Red Sea rift highlight the medium to high geothermal resources in the area. Utilizing an extensive dataset of aeromagnetic data, including derived heat flow (HF) data, geothermal surveys, and radioactive analysis of granitic rock samples, this study employs cutting-edge geophysical methodologies, particularly aeromagnetic data analysis, to identify the structural trends of the study area. The results reveal a range of medium to high heat flow values, determined through meticulous examination of the Curie depth point, temperature gradient, and HF data. Comparative analysis with seismicity data and the structural framework unveils distinct geothermal sources, setting this region apart within Egypt. The observed correlation between high-seismicity areas, structural locations, and HF map locations suggests a significant role of geodynamic motions in shaping the heat flow patterns. By highlighting the substantial geothermal potential, this study underscores the importance of advanced geophysical data in accurately identifying potential energy sources. The insights derived from this research hold global relevance, providing guidance for future exploration and development initiatives and contributing to the international discourse on transitioning to renewable energy. However, a comprehensive evaluation that incorporates radioactive analysis and exploratory drilling is crucial for fully unlocking the geothermal potential in this strategically important study area. [ABSTRACT FROM AUTHOR]

Early Paleozoic A-type granites in South China are rare, and their petrogenesis is still highly debated. This study focuses on the controversial Epo pluton in the Wuyi-Yunkai Orogen and conducts petrological and petrogeochemical research to discuss its origin. The Epo granites were emplaced at approximately 414 Ma and exhibit petrological and geochemical features of A-type granites. They contain only one ferromagnesian mineral, ferrum biotite. The granites mostly have high alkalis contents (Na2O + K2O = 6.48–8.85 wt.%), high field strength element (HFSE) contents (Zr + Nb + Ce + Y = 353–461 ppm), and high Ga/Al (104×Ga/Al = 2.50–3.72) and FeOT/(FeOT + MgO) (0.74–0.85) ratios. Besides, they formed under high-temperature (>850°C) and low-pressure (≤5 kbar) conditions. Their high A/CNK (average 1.20) and Eu/Eu* (average 0.46) values as well as Sr (average 128 ppm) and Ba (average 628 ppm) contents but relatively low Zr contents (approximately 200 ppm) further suggest a strongly peraluminous A-type affinity, a distinctive subtype of A-type granites. The Epo granites display enriched Sr-Nd-Hf isotope compositions with a whole-rock87Sr/86Sri average ratio of 0.712, whole-rock εNd(t) values ranging from − 8.9 to − 7.6, and zircon εHf(t) values clustering at − 8. Their two-stage Nd and Hf isotope model ages are 1.7 Ga to 2.0 Ga, suggesting ancient crustal sources. Furthermore, Nb/U (average 7.46), Ce/Pb (average 4.06) and other trace element ratios indicate negligible contributions from juvenile mantle materials. Our data on the Epo pluton, coupled with other contemporary A-type granites in South China, suggest that the high-temperature melting of metasedimentary basements generated strongly peraluminous A-type granites, while the involvement of metaigneous rocks or mantle-derived magmas resulted in metaluminous to weakly peraluminous A-type granites. Source diversity leads to different aluminium saturations. The heat required to produce high-temperature A-type magmas was supplied by upwelling mantle-derived magma in a postcollisional extensional setting. [ABSTRACT FROM AUTHOR]

K-feldspar megacrysts are common in silicic plutons, but there is a long-running debate around how they form and what their presence tells us about magmatic systems. Field, textural, and geochemical evidence supports growth in a melt-rich environment, but experimental evidence and phase-equilibria modeling indicate that K-feldspar grows late in the crystallization sequence, when the magma is highly crystalline. We provide a new perspective on this problem by examining the arrangement of plagioclase inclusions within megacrysts to test whether they exhibit the systematic low-energy crystallographic relationships expected from attachment by synneusis in melt-rich environments where crystals have space to rotate. We use electron backscatter diffraction to quantify the crystal orientations and find that the megacrysts’ plagioclase inclusions do occupy these preferred orientations and therefore were incorporated in a melt-rich environment. K-feldspar is also present as an interstitial network, but plagioclase crystals hosted within this network have non-systematic orientations. This transition from systematic to non-systematic plagioclase orientations marks the point at which the crystals formed a rigid, interconnected framework that impeded rotation into lowenergy orientations. Phase-equilibria modeling indicates that this transition occurred when the magma was ∼55% crystalline. The remaining ∼45% melt crystallized at the eutectic, forming the interstitial phases. Thus, we resolve the “megacryst paradox”; the megacrysts grew freely in melt, and the groundmass K-feldspar formed after crystal lock-up. Megacrysts therefore provide a detailed textural and chemical record of a critical period in the system’s evolution: the transition from a mobile and potentially eruptible magma to an immobile mush. [ABSTRACT FROM AUTHOR]

To solve the problem of low resolution of seismic data from granite weathering crust and difficulty in predicting effective reservoir distribution. Based on the research idea of combining geology and seismology, seismic facies characteristics and effective reservoir distribution of granite weathering crust are studied by means of frequency division reconstruction processing, seismic facies analysis and sensitive attributes interpretation. This method consists of the following four main processes: (1) Using improved Morlet wavelet function for frequency division and reconstruction processing of seismic data; (2) From the perspective of geological evolution, analyzing the geological origin of seismic facies; (3) Based on the results of well- seismic combination, clarifying the types of effective reservoirs and predicting their distribution; (4) Comprehensive research indicating favorable reservoirs distribution. The results indicate that (1) a considerably improved resolution of seismic data processed by frequency division reconstruction is obtained based on the improved Morlet wavelet function. Thus, granite reservoirs then have clearer internal reflection characteristics. (2) Affected by differences in weathering, the seismic facies in granite weathering crusts can be classified as follows: Strong-amplitude facies with amplitudes of 23,700 − 32,800, corresponding to eluvium, represents the late stage of weathering crust evolution with high-intensity weathering. Medium-amplitude facies with amplitudes of 5,250 − 24,000, corresponding to dissolution layer, represents a middle stage of weathering crust evolution with moderate weathering. And weak-amplitude-blank facies with amplitudes of 0–5,330, corresponding to disintegration layer, represents an early stage of weathering crust evolution with weak weathering. (3) Effective reservoirs can be classified according to well-seismic calibrations and combined with reservoir spaces, porosities and permeabilities, and the logging and oil-bearing characteristics of the reservoirs. Type I effective reservoir comprises medium-amplitude facies, with favorable reservoir conditions and high-yield oil-bearing properties; this type is distributed in the western slopes, with an elevation of 1,300-2,500 m. Type II effective reservoir comprises strong-amplitude facies, with poor oil-bearing properties; this type is mainly distributed in the southeast and north slopes of the study area, with a relatively limited range, and the elevation is mostly below 1,500 m. Type III effective reservoir comprises weak-amplitude-blank facies, with poor reservoir conditions and poor oil-bearing properties; this type is widely distributed at various elevations. (4) The areas where medium-amplitude facies have developed are the most favorable reservoir exploration zones for granite in Dongying Sag, Bohai Bay Basin. [ABSTRACT FROM AUTHOR]

The thermomechanical coupling of rocks refers to the interaction between the mechanical and thermodynamic behaviors of rocks induced by temperature changes. The study of this coupling interaction is essential for understanding the mechanical and thermodynamic properties of the surrounding rocks in underground engineering. In this study, an improved temperature-dependent linear parallel bond model is introduced under the framework of a particle flow simulation. A series of numerical thermomechanical coupling tests are then conducted to calibrate the micro-parameters of the proposed model by considering the mechanical behavior of the rock under different thermomechanical loadings. Good agreement between the numerical results and experimental data are obtained, particularly in terms of the compression, tension, and elastic responses of granite. With this improved model, the thermodynamic response and underlying cracking behavior of a deep-buried tunnel under different thermal loading conditions are investigated and discussed in detail. [ABSTRACT FROM AUTHOR]

In the present study, natural radioactivity and radon exhalation rates of 55 stony material samples divided into three groups (Gneiss, Granite and Marble) were estimated by means of laboratory tests. The activity concentration range was found: 5.5 ± 1.3–125.5 ± 6.5 Bq.kg−1 for 226Ra, 4.4 ± 0.6–157.4 ± 8.4 Bq.kg−1 for 232Th and 35.0 ± 0.4–1093 ± 15 Bq.kg−1 for 40K. The data were used to evaluate radiation hazard parameters. The radon exhalation rate ranged from 0.17 ± 0.01 to 2.56 ± 0.20 Bq.m−2.h−1. Granite building materials show the highest radon exhalation rates while the marble group shows the lowest exhalation rates. Positive correlation coefficients of radon exhalation rate with radium concentration and porosity of the samples have been observed. This study also presents radon diffusion coefficient values determined for 50 waterproofing materials. A radon-proof ability comparison of waterproofing materials and a conclusion about material groups which can be considered very effective radon barriers were discussed. [ABSTRACT FROM AUTHOR]

The geochemical compositions of apatite are commonly used to provide reliable constraints on the intrinsic magmatic variables of the parental magma. There is a widespread distribution of Mesozoic granitic rocks in the eastern Jiangnan Orogen (EJNO), which include I-type and A-type granitoids. This study aims to investigate the geochemical composition of apatite in 11 representative I-type and A-type granitic intrusions from the EJNO to understand their petrogenesis, intrinsic magmatic variables, and polymetallic mineralization potential. The results show that apatites in these granitoids were characterized by oscillatory zonation and homogeneous texture, and exhibited high F, and low Cl contents, as well as high REE, Y, and Th contents, indicating magmatic origin. These apatites were divided into two groups depending on their geochemical characteristics and original rock types. In Group I apatites (in the I-type granitoids), the absence of an abrupt change in major and trace element concentrations from the core to the rim of the apatite crystals, combined with their low levels of MgO, Sr, and HREY (HREE+Y), serves as evidence to classify the I-type granitoids as low Sr-Y adakitic granitoids with a low Mg#, which can be attributed to the partial melting of the thickened lower crust. In Group A apatites (in the A-type granites), the normal increase in incompatible elements from the core to the rim, as well as the presence of a flat REE pattern with pronounced Eu anomalies, can be attributed to crystal fractionation of plagioclase, allanite, and zircon. Furthermore, Group I apatites have higher SO3, Cl, and molar OH/F and Cl/F ratios compared to Group A apatites. Quantitative calculation by apatite-melt partitioning and modelling suggests that the I-type granitic magmas were more volatile-rich and more oxidized than A-type granitic magmas. Taken together, based on the relationship between the intrinsic magmatic variables and the behaviour of ore-forming elements, our study demonstrates that early I-type granitoids of the EJNO have a strong W-Mo-Cu polymetallic mineralization potential, while late A-type granites may possess rare metal mineralization potential. [ABSTRACT FROM AUTHOR]

The Sakarya Zone (northern Turkey) is characterized by the emplacement of voluminous granitoids during the late Carboniferous. In this study, we present geological, U-Pb zircon age, elemental abundance and Sr-Nd-Pb isotopic data on two highly evolved Carboniferous granite bodies within the Early to Late Jurassic volcaniclastic rocks in the Şiran region. The largest body forms a roughly E-W trending ~30 km long and 0.5–2.5 km wide stripe the southern boundary of which is a southvergent thrust, and the other one a subcircular outcrop, ~5 by ~3 km, unconformably overlain by Lower Jurassic volcaniclastic rocks. Their emplacement ages are constrained by LA-ICP-MS U-Pb zircon dating to 310–313 ± 7 Ma (2σ, late Carboniferous). The granitic rocks consist of quartz, microperthitic K-feldspar, plagioclase, and minor biotite, and are characterized by highly evolved compositions with high concentrations of SiO2, Na2O, K2O and Ba, and low concentrations of TiO2, Fe2O3*, MgO, CaO, P2O5 and Sr. Geochemical characteristics indicate a highly fractionated high-K calc-alkaline peraluminous I-type affinity. Chondrite-normalized rare-earth element (REE) patterns are slightly fractionated, with light REEs enriched with respect to middle and heavy ones, and showing variable negative Eu anomalies. On the N-MORB-normalized multi-element variation diagrams, samples display negative anomalies of Ba, Nb, Sr, P, Zr, Eu, and Ti, and positive anomalies of K, and Pb. Initial 87Sr/86Sr and εNd values are 0.70432–0.70610 and −6 to −11, respectively, similar to other Carboniferous high-K calc-alkaline granites and mafic-ultramafic intrusions in the region. The compositional characteristics of the Şiran granites can be explained mainly by fractional crystallization involving hornblende, plagioclase, and biotite and without the involvement of significant amounts of garnet. There is no need to invoke magma mixing and/or melting of a heterogeneous source to account for the geochemical variation. We propose that the late Carboniferous granites formed by remelting of middle- to high-K calc-alkaline mafic rocks at lower crustal depths, followed by extensive fractionation at the upper crustal depths. A thorough review of data from the literature reveals that highly fractionated granites constitute a significant component of the late Carboniferous granites in the Eastern Pontides. [ABSTRACT FROM AUTHOR]

The granitic rocks in the Prachuap Khiri Khan Province, southern Thailand, SE Asia Tin Belt, comprise gneissic biotite monzogranite, porphyritic muscovite–biotite monzogranite, and porphyritic biotite monzogranite. Comprehensive field observations, petrography, mineral chemistry, and geochemistry establish gneissic biotite monzogranites as part of the Central Belt Granites (CBGs), while porphyritic muscovite–biotite monzogranite and porphyritic biotite monzogranite as part of the Western Belt Granites (WBGs). CBG and WBG granitic units exhibit peraluminous, alkali-calcic, and magnesian magmatic series traits, reflecting an S-type granite character resulting from crustal partial melting. Significantly, scatter correlations in variation diagrams, combined with the enrichment of Cs, Rb, Th, U, Pb, Nd, and P, and the depletion of Ba, Nb, and Ti contents, point towards an S-type granite signature formed during collisional events. Crystallization conditions reveal CBG gneissic biotite monzogranite encountered P–T conditions of 2.97–3.85 kbar/680°C–733°C/11.1–14.4 km, while WBG’s porphyritic muscovite–biotite monzogranite and porphyritic biotite monzogranite experienced 2.73–4.15 kbar/628°C–732°C/10.2–15.5 km and 2.47–3.80 kbar/651°C–728°C/9.2–14.2 km, respectively. Geochronological data indicate that CBG’s gneissic biotite monzogranite was emplaced from Early Cretaceous collision (128–119 Ma) of Indochina and Sibumasu terranes, while WBG’s porphyritic muscovite–biotite monzogranite and porphyritic biotite monzogranite were formed during the syn-collision of Sibumasu and West Burma terranes during Early Cretaceous (121–111 Ma) to Paleocene. Mineralogical and geochemical attributes of these granitic rocks exhibit strong relevance to Sn-W mineralization processes, indicative of a profound association. [ABSTRACT FROM AUTHOR]

Characterizing the evolution of mechanical properties of hot dry rock (HDR) after supercritical CO2 (CO2(sc)) injection is crucial for assessing the heat extraction rate and reservoir security of CO2 based enhanced geothermal systems. This study designed the experiments of triaxial seepage and mechanical properties considering no CO2(sc) injection, CO2(sc) injection, and alternating injection of water-CO2(sc) (AIWC) in granite at 150–300 ℃. The experiments can reveal the mechanical properties of HDR in single-phase CO2 zone, CO2-water two-phase zone and dissolved CO2 liquid phase zone in HDR reservoir. The results indicate that the failure mode of the rock samples primarily exhibits sudden instability after no CO2(sc) injection and AIWC, whereas it predominantly manifests progressive instability after CO2(sc) injection. Compared with 25 ℃, the uniaxial compressive strength (UCS) after no CO2(sc) injection at 150–300 ℃ decreased by 13.86%–32.92%. After CO2(sc) injection, the UCS decreased by 40.79%–59.60%. After AIWC, the UCS decreased by 27.74–40.48%. This shows that the strength of rock mass in the single-phase CO2 zone is lower than that in the other two zones, and this weakening phenomenon increases with the increase of temperature difference. At the same temperature, the elasticity modulus after AIWC was greater than that after no CO2(sc) injection and CO2(sc) injection. With no CO2(sc) injection, when the temperature was increased to 200 ℃ and 300 ℃, intergranular cracks and transgranular appeared respectively. After AIWC, mineral crystals such as calcite were precipitated on the surfaces of the connected large cracks, accompanied by kaolinite clay minerals. This increases the frictional contact of the mineral particles and enhances the stability of the HDR reservoir. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Hadani et al. (2024), who used geochemistry and isotopic data to classify the Azegour granite as I-type, suggesting its magma source originated from deep melting of mafic to intermediate rocks in the lower crust. Topics include the granite's geochemical similarity to I-type granitoids; and the possible magma source being influenced by mantle-derived basaltic melts.

Significant potential exists for mining hot dry rock in coastal areas, oceans, islands, and reefs by utilizing abundant seawater as a heat-exchanging medium. It is crucial for optimizing reservoir stimulation technology to explore mechanical characteristics and mechanisms for damage of reservoir rocks during seawater mining of hot dry rock. In this research, granite was subjected to several heat treatment temperatures (100 to 500 ℃) and various numbers of fatigue thermal shocks (0-20) using seawater before Brazilian splitting tests and acoustic emission testing. The findings show that temperature, the thermal shocks, and seawater dissolution are the main factors influencing granite's tensile strength. The temperature threshold for significant degradation of tensile strength, resulting from thermal shock from seawater and heat treatment, ranges from 200 to 300 ℃. At high temperatures (300 to 500 ℃), seawater decreases the tensile strength of granite by approximately 1.67 times compared to freshwater in cycles 0-10, and by about 3.20 times in cycles 10-20. In general, the higher the temperature and frequency of seawater impact, the greater the plasticity of the rock, the lower the tensile strength, and the higher the cumulative count and energy of acoustic emission. The number of seawater thermal shocks and granite's tensile strength have a negative link that is substantially amplified by the temperature. The double effects of seawater cold cycle and heat treatment temperature cause granite to become more porous and progressively shift from tensile to shear damage. These results provide a benchmark for utilizing seawater as a thermogenic medium in enhanced geothermal systems for mineral extraction procedures. [ABSTRACT FROM AUTHOR]

Heat flow data obtained in connection with geothermal resource exploration suggests anomalous upper crustal structure and processes in parts of central east Tasmania. The regional scale crustal geology of the Midlands of Tasmania is, however, mostly obscured at the surface by the Permo-Triassic sedimentary sequences of the Tasmania Basin together with extensive exposures of Jurassic dolerite. We investigate controls on undercover crustal processes in this region by combining long period and broadband magnetotelluric (MT) datasets in 3D inversions for the geoelectric structure; followed by an interpretation that is informed by aspects of the pre-existing 3D regional geological and geophysical model. The new 3D model allows improved resolution of low resistivity anomalies together with a qualitative appraisal of spatially variable model sensitivity. The most robust features ( $ \lt 1\,\Omega {\rm m} $ <1Ωm) in the 2–3 km depth interval occur where N–S and E–W faults intersect with a high point in the topography of the upper surface of a deep seated granite body. Enhancement of conductivity in this zone by clay, graphite or mineralisation, or a combination thereof, is likely. Other low resistivity features suggest that conductive pathways exist where major or multiple faults are present. These interpretations provide support for continued exploration in the Midlands of Tasmania for a variety of resources related to crustal fluids and fracturing. [ABSTRACT FROM AUTHOR]

The Anninghe Fault (ANHF) is a major left‐lateral strike‐slip fault in southwestern China and one of the main seismogenic fault zones with a history of strong earthquakes. To understand the frictional properties of natural granitic gouges from the principal slip zone, we conducted hydrothermal friction experiments using both saw‐cut and ring shear methods. These experiments were performed at temperatures (T) of 25–600°C, pore pressures (Pf) of zero (dry), 30 and 100 MPa, sliding velocities (V) of 0.01–100 μm/s and effective normal stresses (σneff ${\sigma }_{\mathrm{n}}^{\text{eff}}$) of 68, 100, and 200 MPa. The (apparent) friction coefficient is low (μ < 0.5) at high T (600°C), high Pf (100 MPa) and low V (<1 μm/s); but high (μ > 0.6) under all other T, Pf and V conditions. Under high Pf, the velocity dependence of friction, (a‐b), displays three regimes with increasing temperature, from positive below ∼100°C to negative at 100–300°C (at V = 1–3 μm/s) or else 100–450°C (at V = 30–100 μm/s), becoming positive again above 300–450°C. At low Pf, the negative (a‐b) expands to the range ∼300–600°C. Microstructural observations and microphysical interpretation imply that the frictional weakening and transitions in (a‐b) are related to competition between dilatant granular flow and deformation of the fine‐grained gouge by intergranular pressure solution accompanied by healing phenomena (leading to cavitation‐creep‐like behavior). Our results provide a possible explanation for the distribution of earthquakes at different depths in the continental crust, in particular for the depth range of the seismogenic zone between 4 and 24 km along the ANHF. Plain Language Summary: The left‐lateral Anninghe Fault (ANHF), bounding the Tibetan Plateau in China, accommodates part of the distributed convergence between the Indian and Eurasian plates. It has accommodated numerous historical earthquakes during the last few centuries. However, the mechanisms controlling the frictional behavior of natural granitic fault rocks (gouges) collected from ANHF are poorly understood. Laboratory friction experiments were performed at a wide range of temperatures (T), velocities (V) and shear displacements (X), employing varying pore fluid pressure (Pf). The gouges showed potentially unstable shearing behavior at 100–450°C (corresponding to 4–18 km depth), extending up to 600°C (24 km depth) at low Pf (≤30 MPa) and low V (0.04 μm/s). Low frictional strength obtained in large displacement experiments at 600°C indicates a transition from brittle to ductile and seismic‐aseismic (velocity‐strengthening) behavior. Based on microstructural analysis and a microphysical model, we infer that the observed behavior is due to competition between brittle/frictional flow of the granular gouge and creep involving stress‐driven dissolution of the finely crushed constituent grains. Our results offer a possible explanation for the distribution of earthquakes at different depths between 4 and 24 km along the ANHF. Key Points: New experiments confirm a low friction coefficient (μ = 0.37) for granitic gouge at high temperature hydrothermal conditionsThe temperature range characterized by velocity‐weakening narrows with decreasing velocity and with increasing pore fluid pressurePressure solution is a key deformation mechanism controlling the velocity dependence of friction in fine‐grained granite gouge [ABSTRACT FROM AUTHOR]

Weathering process leads to changes in mineral composition, microdefects and mechanical properties of mineral grains, which has a significant impact on the macroscale mechanical properties of granitic rocks. In this paper, four granitic samples with different weathering degrees were investigated using microscale rock mechanics experiments (micro-RME), macroscale rock mechanics experiments (macro-RME) and accurate grain-based model (AGBM). The following conclusions can be achieved. First, quartz is erosionally resistant compared to feldspar and biotite. The weathering products of feldspar and biotite are sericite and chlorite, respectively. Second, with the increasing of weathering degree, the volume fractions of quartz and weathering products increase, meanwhile the volume fractions of feldspar and biotite decrease. Third, during the weathering process, Young's modulus of quartz and feldspar almost keep constant, however, Young's modulus of biotite decreases significantly. Fourth, the weathering process significantly increases the volume of microdefects, including pores and microcracks. Finally, from the viewpoint of the weathering effect, we discovered a negative correlation between quartz content and the macroscale Young's modulus of granites. Highlights: The effect of weathering on the granite at multiscale has been investigated. The quartz is erosionally resistant compared to feldspar and biotite. During weathering process, the strength of quartz and feldspar almost keep constant, however the strength of biotite decreases significantly. During weathering process, the volume fractions of quartz and weathering products increase, and the feldspar and biotite decrease. The weathering process significantly increases the volume of microdefects, including pores and microcracks. [ABSTRACT FROM AUTHOR]

The reconstruction of the Early Paleozoic collision metamorphism of the Khan-Khukhei Block (Northern Mongolia) based on 3D modeling of thermal state of the crust and isotope dating is presented. The age of garnet–biotite schist from a metamorphic complex of the Khan-Khukhei Block of 517.4 ± 7.4 Ma is determined for the first time. 3D modeling was conducted to compare this age of metamorphism with the available age determinations of (post-) collision granite formation in the range of 513‒505 Ma. The model considers radiogenic heating at an elevated heat production of rocks of the thickened crust of the Khan-Khukhei block as the cause of the migmatization and granitoid melts formation. 3D modeling was conducted for the first time for thermal-dome type of metamorphism. The results provide a realistic conception of magma generation in typical collision settings in the absence of mantle magmatic heat sources. The time interval between metamorphism and the stage of anatectic magma formation is 5–12 Ma. [ABSTRACT FROM AUTHOR]

Uranium has been identified as an element of interest for the safety assessment of a deep geological repository for used nuclear fuel. This paper examines the sorption behavior of U(VI) onto MX-80 bentonite and granite in Ca-Na-Cl solutions of varying ionic strengths [0.05 to 3 mol/kgw (m)] and across a pH range of 4 to 10. U(VI) sorption on MX-80 showed that U(VI) sorption gradually increased with pHm until pHm = 6, where it reached its maximum, and decreased slightly with pHm until pHm = 8, and then became constant. U(VI) sorption on granite increased along with pHm, reached the maximum around pHm = 7 to 8, and then slightly decreased with pHm. Both MX-80 and granite showed essentially no ionic strength dependence for sorption of U(VI). A nonelectrostatic surface complexation model successfully predicted sorption of U(VI) onto MX-80 and granite using the formation of an inner-sphere surface complex. Optimized values of surface complexation reaction constants (log K0) for the formation reactions of these surface species are proposed. [ABSTRACT FROM AUTHOR]

The Zhegu area in southern Tibet is situated in the central and eastern part of the Tethys Himalayan tectonic belt, with the Kangbuzhenri area being abundant in gneissic granites. This study examines the petrology, chronology, and geochemistry of the Kangbuzhenri gneissic granite, providing insights into its Pan-African and Early Paleozoic geological evolution. The zircon U-Pb chronology indicates an upper intercept age of ~539 Ma, reflecting Pan-African orogenic events in the eastern part of the Tethys Himalayan tectonic belt, and a lower intercept age of ~144 Ma, representing a late tectonic–thermal event. Geochemically, the gneissic granites are calc-alkaline peraluminous rocks with high SiO2 and Al2O3 contents and low TiO2, P2O5, MgO, and FeOT contents. The gneissic granites are enriched in LREE and LILEs (Rb, Pb, Th, U, etc.), but relatively depleted in HREE and HFSEs (Nb, Ti, P, etc.). Most of them show a weak negative δEu anomaly, except for two samples which show a significant negative δEu anomaly due to the crystallization of plagioclase. Based on the above study, most of the gneissic granites exhibited the characteristics of an I-type granite, while two of the samples were a highly differentiated I-type granite with S-type affinities. All the above characteristics indicate that the gneissic granite likely originated from the partial melting of crustal materials and sediments with a minor involvement of mantle-derived materials. Combined with the previous chronological studies, the Kangbuzhenri gneissic granites were formed in an extensional tectonic environment during post-collision orogeny and then they were influenced by the Kerguelen mantle plume tectonic–thermal event around ~144 Ma and the subsequent Southern Tibet Detachment System (STDS). [ABSTRACT FROM AUTHOR]

The Baoshan deposit is one of the important Cu-Pb-Zn deposits associated with granitic rocks in the Nanling Range, South China. Here, we present He and Ar isotope data for the Baoshan deposit to decipher the contributions of mantle-derived volatiles and heat to its Cu-Pb-Zn mineralization. The ore-forming fluids in sphalerite and pyrite exhibited 3He/4He ratios up to 1.51 Ra. A linear correlation between He and Ar isotopes suggests that the ore-forming fluids were a mixture of a predominantly mantle-derived fluid with a high 3He/4He ratio and a shallow crustal fluid, characterized by a low 3He/4He ratio. The δ34S values of sulfides in the Baoshan deposit ranged from +2.30 to +5.21‰, consistent with the magma-derived sulfur. The calculated 3He/Q ratios for the ore-forming fluid exceeded those of mid-oceanic ridge hydrothermal solutions by 10 to 50 times, indicating that the ore-forming fluids acquired both heat and volatiles in a convective hydrothermal regime rather than a conductive one. Therefore, there is a significant contribution of mantle-derived volatiles, heat, and possibly metals, to the Cu-Pb-Zn mineralization in the Baoshan deposit, and the continuous influx of mantle-derived fluids/melts probably plays a crucial role during the Cu-Pb-Zn mineralization related to granitic rocks. [ABSTRACT FROM AUTHOR]

The South China Plate is an important part of the Rodinia supercontinent in the Neoproterozoic. The Rizhao area, located on the northeastern margin of the South China Plate, records multiple periods of magmatism, among which Neoproterozoic granitic gneiss is of great significance to the tectonic evolution of the South China Block. In this study, systematic petrology, geochemistry, isotopic chronology, and zircon Hf isotopic analyses were carried out on gneisses samples of biotite alkali feldspar granitic and biotite monzogranitic compositions in the Rizhao area. Geochemical analyses suggest that these granitic rocks belong to the sub-alkaline series and have high potassium contents. They are enriched in large-ion lithophile elements K, Rb, and Ba; depleted in high field strength elements P, Nb, and Ti; enriched in light rare earth elements and moderately depleted in heavy rare earth elements; and have weak to moderate negative Eu anomalies and weak negative Ce anomalies. These rocks are post-orogenic A-type granites. LA-MC-ICP-MS U-Pb dating of zircons from two biotite alkali-feldspar granitic gneiss samples yielded weighted mean ages of 785 ± 8 Ma (MSWD = 3.0) and 784 ± 6Ma (MSWD = 1.5), respectively, and a biotite monzogranitic gneiss sample yielded a weighted mean age of 789 ± 6 Ma (MSWD = 2.3). Lu-Hf isotopic analyses on zircon grains from the two types of Neoproterozoic-aged gneisses yielded negative εHf(t) values ranging from −19.3 to −8.8 and from −18.3 to −10.4, respectively, and the corresponding two-stage Hf model age ranges are 2848–3776 Ma and 2983–3682 Ma, respectively. These granites are the product of Neoproterozoic magmatic activity and are mainly derived from the partial melting of Archean continental crust. Combining the geochemical characteristics and zircon U-Pb-Lu-Hf isotopic analyses, these A-type granitic gneisses appear to have formed in an intracontinental rift extension environment during the initial break-up of the Rodinia supercontinent, as part of the supercontinent break-up process at the northeastern margin of the South China Block. [ABSTRACT FROM AUTHOR]

The Neoproterozoic granitic rocks of Mount Abu Kibash and Tulayah in the central Eastern Desert of Egypt are of geodynamic interest and provide us with important information about the evolution and growth of the northern part of the Arabian–Nubian Shield (ANS) continental crust. They are primarily composed of granodiorites and syenogranites based on new field, mineralogical, and geochemical analyses. The granodiorites are marked by an enrichment of LILEs such as Sr, K, Rb, Ba compared to HFSEs like Nb, Ta, Ti and show a higher concentration of LREEs relative to HREEs. This composition suggests a subduction-related setting and aligns with the characteristics of subducted I-type granites in the ANS. Chemistry of the analyzed primary amphiboles in the investigated granodiorites support a calc-alkaline nature, mixed source and subduction-related setting. The granodiorites represent an early magmatic phase in this setting, likely formed from a mix of mantle-derived mafic magmas and lower crust material, with subsequent fractional crystallization. On the other hand, syenogranites exhibit high SiO2 (72.02–74.02 wt%), total alkali (7.82–8.01 wt%), and Al2O3 (13.79–14.25 wt%) levels, suggesting their derivation from peraluminous (A/CNK > 1) parental magmas. Their REE-normalized patterns are flat with a pronounced negative Eu anomaly, typical of post-collisional A2-type granites worldwide. These rocks originated from the partial melting of a juvenile lower crustal source (tonalite) in a post-collisional setting, driven by lithospheric delamination that facilitated mantle upwelling and underplating to the lower crust. Interaction between the upwelled mantle and lower crust led to fertilization (enrichment with HFSE and alkalis) of the lithosphere before partial melting. Fractional crystallization coupled with less considerable crustal assimilation are the main magmatic processes during the evolution of these rocks. The transition from subduction to post-collisional setting was accompanied by crustal uplifting, thickening and extensional collapse of ANS continental crust that caused emplacement of large masses of A-type granites in the northern ANS. [ABSTRACT FROM AUTHOR]

Alteration in greisen-type granites develops through the progressive replacement of feldspars by potassic micas. Under the name 'greisen', quartz–muscovite assemblages display differences and include a variety of facies with variable relative proportions of quartz and muscovite. In principle, feldspar conversion to muscovite is written usually considering constant aluminium, and should result in a modal proportion of six quartz plus one muscovite. In Beauvoir greisens, which result from albite-rich granite, the relative proportion of quartz–muscovite is in favour of muscovite. Such a balance results from a reaction that implies imputs of potassium and aluminium, thus different from the classic one. The Q'-F' diagram provides a graphical solution for discriminating between reaction paths. A representative series of greisen data from the literature is compared in this diagram: Beauvoir B1 unit, Cligga Head, Cinovec, Panasqueira, Zhengchong, and Hoggar. [ABSTRACT FROM AUTHOR]

Three boreholes drilled during the International Ocean Discovery Program (IODP) Expedition 396 have yielded unexpected findings of altered granitic rocks covered by basalt flows, interbedded sediments and glacial mud near the continent‐ocean transition of the mid‐Norwegian margin. U‐Pb and K‐Ar geochronological analyses were conducted on both protolithic and authigenically formed K‐bearing minerals to determine the age of granite crystallisation and subsequent alteration episodes. The granite's crystallisation age based on 104 zircons is 56.3 ± 0.2 Ma, and subsequent exhumation along with alteration/weathering events took place between 54.7 ± 1 and 37.1 ± 1 Ma. This intrusion represents the youngest granite discovered in Norway and intruded at an extremely shallow crustal level before a rapid rift‐to‐drift transition. The shallow emplacement of granitic rock and its fast exhumation before and during the onset of volcanism holds significant implications for the syn‐ and post‐breakup tectonic evolution of volcanic margins. [ABSTRACT FROM AUTHOR]

An efficient two-step microwave-assisted digestion (MWD) method using a dilute acid mixture for the total dissolution of granite materials for the quantitative determination of rare earth elements (REEs) and other elements including high field strength elements (HFSEs) by inductively coupled plasma optical emission spectrometry (ICP-OES) was developed. In the first step, 8 mL of an acid mixture containing 20% (v/v) HF + 25% (v/v) HCl + 10% (v/v) HNO3 was added to the ~0.25 g of granite sample and the MWD procedure was carried out. After completion of the first step of the MWD process (MWD-1), the sample mixture was transferred to a graphite bottom Teflon beaker and evaporated on a hot plate at 150 °C to incipient dryness for the removal of the silica matrix (evaporation step (ES)). The residual sample matrix was redissolved in 8 mL of an acid mixture containing 20% (v/v) HCl + 20% (v/v) HNO3 and further subjected to the second step of the MWD process (MWD-2) for its total decomposition. The complete sample treatment protocol [MWD-1 (1.5 h) + ES (1 h) + MWD-2 (1.5 h)] requires only about 5 h, including cooling steps. The final sample digests were very clear with no fluoride precipitates indicating complete decomposition of different phases present in the granite material. After suitable dilution, the final and clear sample digests were analysed for REEs (La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb, Sc and Y), HFSEs (Ti, Zr, Nb, Hf and Th) and other elements (Al, Ca, Fe, Sr and Ba) by ICP-OES. Critical experimental parameters related to MWD processes were optimized for achieving quantitative recovery (>95%) for most of the considered analytes. The accuracy of the method was validated through the analysis of two certified reference materials SARM-1 and NCS DC 73376. The optimized approach (MWD-1 + ES + MWD-2) was subsequently applied to multiple granite samples collected from different geological origins. These investigations clearly demonstrate that the proposed sample preparation method using a dilute acid mixture in conjunction with ICP-OES has great potential for the quantitative determination of REEs, HFSEs and other elements in large batches of granite materials, generated in mineral exploration studies. [ABSTRACT FROM AUTHOR]

The paper discusses possible immiscibility between fluoride salt ("cryolite") and silicate liquids into which the parental melt of the Katugin massif exsolves, and the petrological implications of this phenomenon. Results of a detailed study of the cryolite and zircon are presented. Liquid immiscibility is demonstrated to have triggered the massive crystallization of zircon and, together with the processes of subsequent evolution of the cryolite melt, contributed to the formation of the large cryolite bodies. Data on mineral-hosted inclusions were used to estimate the crystallization temperatures of fluoride salt and silicate melts and outline the pathways of their evolution during the formation of the massif. It is shown that the granites of the Katugin and West Katugin massifs were most likely derived from distinct sources, that differed mainly in fluorine content. Data on the chemical composition of three zircon generations identified in the granites of the Katugin massif are presented. [ABSTRACT FROM AUTHOR]

Granite is a common engineering material that exhibits complex mechanical properties under external loads. This study conducted experimental research and analysis in conjunction with the active monitoring technology of piezoelectric ceramics. A quantitative analysis method for the mechanical properties of rock materials based on piezoelectric health monitoring was established, and for the first time, the piezoelectric monitoring results of rock were mapped and compared with the uniaxial compression performance indicators of rock. In this study, two sets of cyclic impact experiments were conducted on granite samples using a drop hammer. The piezoelectric signals of the granite samples were detected using piezoelectric ceramic active sensing technology. A piezoelectric ceramic damage monitoring method was proposed, and the damage factor of the granite samples was calculated using the wavelet packet energy method. Subsequently, uniaxial compression experiments were performed on the damaged granite samples to obtain mechanical performance data. Finally, a mathematical relationship model was established between the piezoelectric signal and the uniaxial compressive strength of the rocks. It was found that the damage factor of the piezoelectric monitoring signal of the damaged rock were linearly related to the uniaxial compressive strength of the damaged rock. [ABSTRACT FROM AUTHOR]

The quantification microstructural parameters has gained significant attention to estimate the strength of rock materials. Some researchers have qualitatively explained the influence of microstructural parameters on rock mechanical properties and many developed empirical relations between various microstructural indices and engineering properties of different rock types. A comprehensive review on the relation between microstructure and strength of rock materials has been carried out in this study based on the available literature and the tests performed on granite and sandstone from Malanjkhand and Kothagudem respectively. It has been observed that the correlation of rock strength with mineral content, textural parameters and micro-crack patterns does not signifies any perceptible correlation or any definite trend. This is attributed to the fact that rock strength is a manifestation of cumulative responses of a number of microstructural parameters and thus, correlating rock strength with any single parameter would overlook the impact of others. The study also discusses the challenges and potential benefits of both quantitative and qualitative analysis of microstructure in rock mechanics, providing a way forward for future research in the field. It is ascertained that microstructural studies are time consuming approach and involve significant limitations when quantifying the parameters from the microscopical images and relating them individually with strength of the rocks. However, they might be an important aspect in comprehending the variation in strength and deformation of rock materials and in this respect the implication of modern technological setups would be efficient over the conventional methods. [ABSTRACT FROM AUTHOR]

This paper records the results of a pioneering exploration borehole drilled in 1984 to a depth of 403.84 m in the London Basin and underlying London–Brabant basement high. The key objectives of the project were to measure the equilibrium temperature in the Paleozoic basement, estimate the temperature gradient after climate impact corrections and assess the heat flow in the area. From this, estimates of temperature at depths of 2000 m could be made with a view to evaluating potential geothermal resources. From the downhole measurements, a temperature gradient of 16°C km−1 was estimated with a temperature range between 46°C and 51°C at a depth of 2000 m, considered to be consistent with other UK sites where there is no contribution from high heat production granites. The results of the Thamesmead exploration borehole suggested that the geothermal potential of the Devonian and the Paleozoic basement below London is poor, and no further work was carried out. The work has remained unpublished until now but in view of the current renewed interest in geothermal resources it is appropriate to make the work public. Although the results were not encouraging, they do remain as a contribution to the revitalized assessment of geothermal resources in the London area and the UK in general. [ABSTRACT FROM AUTHOR]

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The Cornubian Batholith (SW England) is an archetypal Variscan rare metal granite with potential for Li-mica mineralization. We present a petrographic, trace element and multivariate statistical study of micas from the Cornubian Batholith granite series and related hydrothermally altered units to assess the role of magmatic vs subsolidus processes and of fluxing elements (F and B) on the Li cycle during the evolution of the system. The mica types are as follows: (1) magmatic, which include Fe-biotite, protolithionite I and phengite-muscovite from the most primitive granites, and zinnwaldite I from more fractionated lithologies; (2) subsolidus, which encompass high-temperature autometasomatic Li-micas and low-temperature hydrothermal muscovite-phengite. Autometasomatic species include protolithionite II, zinnwaldite II and lepidolite, which were observed in the most fractionated and hydrothermally altered units, and occur as replacements of magmatic micas. Low-temperature hydrothermal Li-poor micas formed via alteration of magmatic and autometasomatic micas or as replacement of feldspars, and albeit occur in all studied lithologies they are best represented by the granite facies enriched in metasomatic tourmaline. The evolution of micas follows two major trends underlining a coupling and decoupling between the Li(F) and B fluxes. These include as follows: (1) a Li(F)-progressive trend explaining the formation of protolithionite I and zinnwaldite I, which fractionate Li along with Cs, Nb and Sn during the late-magmatic stages of crystallization, and of zinnwaldite II and lepidolite forming from the re-equilibration of primary micas with high-temperature Li-B-W-Tl-Cs-Mn-W-rich autometasomatic fluids; (2) a Li(F)-retrogressive trend explaining the low-temperature hydrothermal muscovitization, which represents the main Li depletion process. Trace element geochemistry and paragenesis of late muscovite-phengite support that muscovitization is a district-scale process that affected the upper parts of the granite cupolas through acidic and B(Fe-Sn)-saturated hydrothermal fluids associated with metasomatic tourmalinization, which were mixed with a low Eh meteoric component. [ABSTRACT FROM AUTHOR]

Effective geochemical anomaly identification is crucial in mineral exploration. Recent trends have favored deep learning (DL) to decipher geochemical survey data. Yet purely data-driven DL algorithms often lack logical explanations and geological consistency, occasionally clashing with known geological insights and complicating model interpretation. A deep understanding of the geological processes forming the target mineral deposit is vital for accurate anomaly detection. Here, we introduce an adversarial autoencoder (AAE) network that integrates prior geological knowledge to identify geochemical anomalies linked to tungsten mineralization in southern Jiangxi Province, China. Considering the geochemical patterns linked to tungsten mineralization, Yanshanian granites and faults were strategically chosen as ore-controlling factors. The methodology employed multifractal singularity analysis to quantitatively measure the correlations between these ore-controlling factors and known tungsten deposits, aiming to establish an ore-forming regularity. This regularity serves as a priori distribution to control the encoder network's latent vector, refining the model's output. A comparison of detected geochemical anomalies under different constraints (AAE, Granite_AAE, Fault_AAE, and Fault_Granite_AAE) revealed that AAE models incorporating prior geological information consistently outperformed unconstrained models in terms of anomaly detection. Integrating geological expertise with DL, our study overcomes the challenges of models relying purely on data or theory, offering a promising approach to geochemical exploration. [ABSTRACT FROM AUTHOR]

We introduce a new methodology for inference of fluid composition from measurements of mineralogical or chemical compositions, expanding upon the use of reactive transport models to understand hydrothermal alteration processes. The reactive transport models are used to impute a latent variable explanatory mechanism in the formation of hydrothermal alteration zones and mineral deposits. An expectation maximisation algorithm is then employed to solve the joint problem of identifying alteration zones in the measured data and estimating the fluid composition, based on the fit between the mineral abundances in the measured and predicted alteration zones. Using the hydrothermal alteration of granite as a test case (greisenisation), a range of synthetic tests is presented to illustrate how the methodology enables objective inference of the mineralising fluid. For field data from the East Kemptville tin deposit in Nova Scotia, the technique generates inferences for the fluid composition which compare favourably with previous independent estimates, demonstrating the feasibility of the proposed calibration methodology. [ABSTRACT FROM AUTHOR]

The adhesion property has consistently been a critical focus in the utilization of recycled asphalt (RA). This research aimed to elucidate the mechanisms influencing the adhesion property of RA at various scales. Specimens of base asphalt (BA), aged asphalt (AA), and RA were systematically prepared. The impacts of aging and rejuvenators on the nano adhesion property of asphalt were assessed using multi-scale testing methods. The findings revealed that aging adversely affected the adhesive interaction between BA and aggregate, whereas the application of rejuvenators substantially improved this effect. When compared to acidic aggregate of granite, the alkaline aggregate of limestone demonstrated superior adhesion properties with RA. Moreover, the correlation analysis affirmed that mechanical testing across various scales consistently evaluated the trends in the adhesion property of RA with aggregates. [ABSTRACT FROM AUTHOR]

Crack stress thresholds in rocks have long been a popular subject in rock mechanics and engineering research. In this study, the applicability of existing methods for determining the crack stress thresholds of granite and weakly cemented porous siltstone is investigated using step loading and unloading tests. In addition, a novel method for decomposing the volumetric strain into solid-phase linear elastic strain, gas-phase nonlinear elastic strain, and plastic volumetric strain is presented. A quantitative calculation method for determining these thresholds is proposed based on the evolution law of the gas-phase volumetric strain and the physical significance of crack stress thresholds. The initiation and termination points of the stationary stage of the gas-phase volumetric strain are determined as σ cc and σ ci ; the point at which the gas-phase strain changes from positive to negative is determined as σ cd . To validate the proposed method, statistical results of the existing methods after screening are compared with the results of the proposed method. The results show that the proposed method provides reasonable crack stress thresholds for siltstone and granite and is applicable to rocks with similar stress–strain behaviors. The proposed method offers the advantages of independence from other methods, suitability across high and low confining pressures, and the capability for the quantitative calculation and processing of numerous samples. [ABSTRACT FROM AUTHOR]

This research work aims at evaluating the geothermal energy potentials of the Rafin Rewa warm spring (RRWS) of the Precambrian Basement Complex in Nigeria as an alternative energy source using integrated aeromagnetic geophysical techniques. Four aeromagnetic dataset were acquired, assemblage, analyzed, and interpreted using integrated geophysical processing techniques of spectral analysis and Euler deconvolution. Qualitative interpretation of the residual anomalous map reveals a distribution of positive anomalies (> 53 nT) majorly in the central and southeastern regions, which are traced to the granitic rocks, while the low anomalies (< − 1.5 nT) have been traced to the RRWS location emanating from the coastal plain sands of the Pliocene, Pleistocene, Oligocene, and Miocene ages. Quantitatively, the depth to the top (DTT) of the anomalous bodies reveals a depression that is almost intersecting with the Curie point depth (CPD) plot at the RRWS location, which indicates high heat flow in the RRWS region. The Spectral Analysis results reveal that the DTT and the CPD in this area ranges from 0.512 to 0.761 km and 6.504 to 10.582 km, respectively while the average CPD is 8.543 ± 0.325 km. It is observed that the DTT and CPD decrease as one move away from the RRWS region. The computed heat flow average was 160.76 ± 19.09 mW/m2 within the RRWS region. The Euler deconvolution result reveals the presence of geological structures, which were interpreted as faults and fractures. The major fractures trend in the east–west (E-W) directions, while the minor fractures trend northeast-southwest (NE-SW) directions. The geochemical result presented shows that iconic compositions impact the convective heat transfer processes associated with geothermal systems. It was conclusively believed that regions with comparable shallow CPDs could be viable for further geothermal energy investigations. [ABSTRACT FROM AUTHOR]

To investigate the damage mechanisms in granite's physical and mechanical properties after high-temperature water quenching, this study employed MTS815.04 for uniaxial compression tests on thermally treated specimens, with concurrent acoustic emission monitoring, and utilized nanoindentation for micromechanical analysis. The results show that with increasing temperature, granite's peak strength and elastic modulus decrease, with a sharp decline after 400–500 °C, corresponding to a significant increase in the internal damage, which can be detected by acoustic emission monitoring. Below 500 °C, macroscopic mechanical degradation is due to mineral thermophysical property differences, while above 500 °C, microcrack development is the main deterioration factor. The failure mode shifts from tensile to tensile-shear complex to shear failure, with transition points at 400 °C and 800 °C. The results of this study are of certain reference value for improving the efficiency of extracting thermal energy from dry-hot rocks and providing security guidance for the tunnel restoration process following fire damage. [ABSTRACT FROM AUTHOR]

Microwave rock fracturing has a wide range of application prospect in deep resource development due to its advantages of high efficiency and energy saving, and the study of damage in the fracturing process is of great importance in guiding the safety and high efficiency of rock fracturing. However, damage characterisation during microwave rock fracturing has not been sufficiently investigated. Therefore, studying the characteristics of crack propagation and evolution during microwave heating is of great significance. This paper investigates the crack evolution characteristics and failure mechanism of granite under microwave irradiation by collecting the real-time acoustic emission signals during heating using the self-developed microwave hot rock damage real-time dynamic monitoring system. The results indicate similar change characteristics of the real-time acoustic emission counts, energy, and RA/AF values of rock samples with corresponding stages after 900 s of microwave power irradiation at 0.3 kW, 0.6 kW, and 0.9 kW under the same temperature range and the most active acoustic emission range is 200–310 °C. The degree of thermal damage to rock samples and the power show a positive correlation under similar temperature ranges. The characteristics of real-time RA/AF values reflect the tensile failure of granite during microwave heating, accounting for more than 65%. However, the shear crack ratio increases with irradiation time or power, with the highest ratio of 33.3%. In addition, the real-time acoustic emission curve in the microwave heating process reaches the acoustic emission active point at 200 °C, which is far less than 300 °C and 350 °C of the traditional conduction heating method, with 1/2th and 1/15th of the heating time of the traditional conduction heating method, indicating the superiority of microwave rock breaking. [ABSTRACT FROM AUTHOR]

The distribution coefficient (Kd) of radionuclides is a crucial parameter in assessing the safety of high-level radioactive waste (HLW) geological repository. It is determined in the laboratory through batch and column experiments. However, differences in obtained Kd values from distinct experiments have not been thoroughly assessed and compared. This study evaluated strontium (Sr) sorption on different granite materials using static batch and dynamic experiments (column and core-flooding experiments). The results from batch sorption experiments showed higher Sr sorption on granite under acidic and strongly alkaline conditions, low solid–liquid ratios, and low ionic strength. In column experiments, a two-site sorption model was used to simulate Sr transport in crushed granite and mixed pure minerals. The sorption of Sr on crushed granite exhibited a higher affinity than that of mixed pure minerals. The dual-porosity transport model was employed to investigate Sr transport behavior in fractured granite in the core-flooding experiment. Kd obtained from batch sorption experiments are four to twenty times higher than those from column experiments, and two to three orders of magnitude higher than that from a core-flooding experiment. The results of this study provide valuable insights into safety assessment for the HLW geological repository. [ABSTRACT FROM AUTHOR]

Introduction: The early Jurassic granitoids in the Qinling Orogenic Belt (QOB) play a crucial role in understanding the tectonic implications for the geological evolution of China. To elucidate the early Jurassic tectonic setting of QOB, we performed a comprehensive analysis of zircon U-Pb ages, whole-rock geochemistry, and in situ zircon Lu-Hf isotopes from early Jurassic monzodiorite and Kfeldspar granite within the Baoji batholith in western QOB. Geochronology Method and Results: The intrusions yielded zircon U-Pb ages of 186 ± 2 Ma and 188 ± 2 Ma, respectively. Geochemistry Results: The monzodiorites are characterized by relatively high MgO, Rb, Th, U, and LREE contents, as well as low P, Ti, and HREE contents. They also exhibit high Nb/Ta ratios (20.6-23.4). The zircon ε[sub Hf](t) values for the monzodiorite sample range from -4.36 to 6.47, indicating significant contributions from a fertile continental lithospheric mantle with the involvement of crustal components. The K-feldspar granites are enriched in K2O+ Na2O, Rb, Zr, Hf, and Nb, and lower Ba, Sr, Ti, and P. They exhibit high Nb/Ta and Ga/Al ratios but low Y/Nb and Yb/Ta ratios. Their geochemical characteristics reveal an A-type granite affinity with elevated zircon saturation temperatures (848°C-900 °C). Additionally, the K-feldspar granite exhibits REE and trace element patterns similar to those observed in the monzodiorite. However, a wide range of zircon εHf(t) values (-4.72 to 3.98), differing from those of the monzodiorite, indicate that the parental magma of the K-feldspar granite experienced magma mixing between a monzodioritic magma and a crustal-derived felsic magma. Discussion: These findings suggest that both A-type K-feldspar granite and monzodiorite likely formed during post-orogenic processes. Additionally, the QOB commenced its postorogenic evolution as an extensional tectonic environment during the early Jurassic period. [ABSTRACT FROM AUTHOR]

Sparse felsic microgranitoid enclaves (FMEs) in the Shangshuiquan granite of the Zhangjiakou district, the north margin of the North China Craton, are fine‐grained, dark‐colored and exhibit subangular to subspherical shapes. They share similar mineral assemblages, chemical compositions, and zircon Hf isotope compositions to the host granite. New zircon U‐Pb geochronology reveals that the FMEs crystallized at 156–153 Ma, while the Shangshuiquan granite formed at ca. 146 Ma. The FEMs are, therefore, 10 to 7 Ma older than the host granite. Combined with petrological evidence, we suggest that the FMEs are fragments of rapidly crystalized magmas, which were captured by the younger Shangshuiquan magma. Magmas of the FMEs and Shangshuiquan granite originated from the same reservoir. The Shangshuiquan granite is the result of small batches of magma being built up incrementally, and the FMEs belong to the earlier batches of magma. The lifespan of the Shangshuiquan magma reservoir exceeds 10 Ma. FMEs derived from cogenetic fragments have the potential to offer critical information about the formation process and timescale of granitic plutons. [ABSTRACT FROM AUTHOR]

In this study, granite wastes based glass-ceramics containing Eu 2 O 3 as simulated radionuclides is successfully synthesized via solid-state sintering method. The structure, mechanical properties and chemical durability are deeply investigated. The main phase in this glass-ceramics is oxyapatite (Ca 2 Eu 8 (SiO 4) 6 O 2), which is dispersed homogenously in glass matrix. The density dominates the properties of Vickers hardness and bending strength. The glass-ceramics containing 40 wt % of Eu 2 O 3 has the optimal mechanical properties, with the Vickers hardness, bending strength and density of 5.12 GPa, 79.44 MPa and 98.77 %, respectively. The 28 days leaching experiments show that the glass-ceramics containing 40 wt % of Eu 2 O 3 possess excellent chemical durability. The leaching rate of Al3+, Si4+, Fe3+, Ca2+, Eu3+ are 2.3 × 10−4 g m−2 d−1, 6.0 × 10−4 g m−2 d−1, 1.2 × 10−7 g m−2 d−1, 1.4 × 10−4 g m−2 d−1, 3.6 × 10−8 g m−2 d−1, respectively. This study indicates that granite wastes based glass-ceramics have excellent chemical stability and mechanical properties, which provides a novel idea for the immobilization of radioactive wastes. [ABSTRACT FROM AUTHOR]

In the geothermal development of hot dry rock (HDR), both the drilling of the wellbore and the heat exchange of the heat reservoir involve the effects of different cold and hot conditions on the high-temperature rock mass. The testing machine for rock mechanics was used to conduct a uniaxial compression test and carry out micro testing on the treated samples; furthermore, with the help of scanning electron microscopy the fracture mechanism of granite subjected to different temperatures and cooling methods was studied. The results show: (1) With the gradual increase in temperature, the compressive strength of granite under the two cooling methods gradually decreases. (2) The failure modes of the samples under the two cooling methods are mainly shear failure of the "Y" type. The degree of damage of the sample under water cooling is significantly greater than that under natural cooling. Electron micrographs could confirm these results. (3) It can be obtained by testing the mineral composition and element changes of granite at different temperatures. When the temperature reaches 600℃, its change is more pronounced. The results of this study can provide a theoretical reference for the failure of the wellbore and the degree of fracture of the thermal reservoir rock mass during geothermal development. [ABSTRACT FROM AUTHOR]

The variability of magmatic zircon geochemical signatures can reecord different tectonic settings and be used to accurately determine regional tectonic evolution. For example, Th/U values of magmatic zircons correlate with tectonic stress regimes (continental extension and compression) and the magmatic environment. Previously, the Karamaili Granite Belt (KGB) has been considered to be a product of siliceous magmatic activity in the late Palaeozoic post-collisional extensional environment of the Eastern Junggar, and consensus is that it is composed of A2-type granite. In this study, the U-Pb zircon geochronology of the KGB indicates it crystallized between 320 and 310 Ma. The Th/U ratios of the 494 magmatic zircons range from 0.22 to 1.22 but in the southeastern part of the KGB exhibit high Th/U ratios (maximum 1.22) and high coefficients of variation (maximum 45.2%), compared to the smooth Th/U variation (mostly <0.8) and low coefficients of variation (minimum 13.5%) in the northwestern part. The δEu values of zircons in the KGB range from 0.1 to 1.16, with less variability (mostly <0.2), but show an increasing trend in the extensional area (maximum 1.16). Zircon trace element signatures indicate that the most KGB granites exhibits highly differentiated I-type granite characteristics. In addition, tin mineralization in the KGB is primarily controlled by a tectonic environment of compression and is closely associated with highly differentiated I-type granites. This is distinctly different from granites with mafic microgranular enclaves (MMEs), such as those in the Sabei and Huangyangshan plutons, which formed in an extensional environment with significant crustal growth. Hence, the Th/U and δEu indicators of zircons suggests the KGB was formed during a tectonic transformation of overall compression and local extension at the end of plate subduction, and a local extensional environment was formed at the Junggar Ocean end of the subduction in this area, which introduced large-scale mantle-derived material of mantle origin, and that crustal vertical growth was strong, forming a thicker juvenile crust. [ABSTRACT FROM AUTHOR]